Project description:Hemolymph was characterized from Diaphorina citri adults infected with the phytopathogen, Candidatus Liberibacter asiaticus (CLas) and compared with that from uninfected psyllids. This study identified 5531 and 3220 peptides within infected and uninfected hemolymph using nano LC-MS/MS. A reduced number of proteins were detected for D. citri and all known endosymbionts within infected hemolymph as compared to uninfected hemolymph. A large number of immune defense proteins were absent from D. citri hemolymph; however, a single recognition protein (PGRP), two serine protease inhibitors, three prophenoloxidase (proPO) enzymes, and a single serine protease in an uninfected D. citri were detected. The hemolymph is nearly devoid of nutrient storage proteins. This is the first proteomic analysis of D. citri hemolymph that also analyzes the components contributed by all of the endosymbionts. By comparing the contribution of each endosymbiont (CCR, CPA,WB) in the presence and absence of CLas infection, this study provides initial insights regarding the hemolymph response to microbial community shifts associated with D. citri infection status. Our data also present potential protein targets for analysis and disruption of CLas transmission that may facilitate management of huanglongbing (HLB) caused by CLas in citrus.
Project description:Diaphorina citriis a vector of ‘CandidatusLiberibacter asiaticus,’(CLas), associated with citrus greening or Huanglongbing (HLB) disease in citrus. D. citriexhibits two group three different color morph variants, blueand non-blue (includes gray and yellow). Blue morphs have a greater capacity for long-distance flight while has lower efficiency in CLas transmission as compared to non-blue morphswhich influences disease epidemiology. In this study, wecompare the protein profilesof two-color morphsand evaluate the effect of CLas infection on abundance of pre-identified proteins in each color morphs. Our results showed that blue morphs have higher abundance of the immunity-associated proteins, while their abundance were upregulated dramatically in the non-blue morphcompared to blue morphin result of CLas infection. This observation proposes blue morph has higher immunity and CLas trigger the immunity in both morph while in non-blue’s response is late and non-effective.Further, challenging both color morphs byentomopathogenic fungi Beauveria bassiana, were showed significantly lower mortality in blue morph vs non-blue. Also, to test the effect of delayed response in CLas acquisition, we did CLas acquisition assay after priming immunity by feeding heat-killed Liberibacter crescens to both color-morphs. The obtained results were showed that priming immunity in non-blue morph can significantly decrease CLas acquisition as close as the level of CLas acquisition in blue morph. Taking all these in account propose that higher immunity in blue morph suppress CLas acquisition in a way that CLas acts as a pathogenand costly forACP. While in non-blue ACP, CLas triggers the immunity but the delayed immunity is not effective to block CLas from acquisition.
Project description:Purpose: We obtained RNA-seq-based differential expression profile of Valencia sweet orange plants challenged against healthy and CLas-infected psyllid infection at 1 dpi and 5 dpi. The goals of this study are to reveal the interaction between citrus and psyllid/CaLas during the early phase of infection and understand the molecular mechanisms underlying the host-pathogen interactions and the susceptibility of most citrus varieties. Methods: leaf mRNA profiles of in vitro cultured Valencia sweet orange (VAL) budwood (WT) and of VAL fed by healthy and CLas-infected psyllid were generated by RNA-seq, in triplicate (one sample is duplicate), using Illumina HiSeq platform. The sequence reads that passed quality filters were used for gene expression and DEG detection analysis by EBseq algorithms. qRT–PCR validation was performed using SYBR Green assays Results: Using the RNA-seq data analysis workflow, we mapped about 136.80M sequence reads per sample to the reference Citrus clementina v1.0 genome and a total of 32,677 genes were detected. The average total mapping of each library was 71.98%. RNA-seq data were validated with qRT–PCR. Conclusions: Our study obtained the transcriptional profiles of citrus host by feeding of psyllid transmitting Candidatus Liberibacter asiaticus at early stages of infection, with biologic replicates, generated by RNA-seq technology. The RNA-seq data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. We conclude that RNA-seq based transcriptome characterization would expedite genetic network analyses and permit the dissection of complex biologic functions.
Project description:Identification of protein interactions within Asian citrus psyllids exposed to the citrus greening bacterium, Candidatus Liberibacter asiaticus.
Project description:Huanglongbing (HLB) is a devastating disease of citrus plants caused by the non-culturable phloem-inhabiting bacterium Candidatus Liberibacter asiaticus (CLas). Bacteria are vectored by the psyllid Diaphorina citri and introduced into sieve cells, evading plant immunity and establishing a successful infection in citrus plants. Although no resistance has been reported in Citrus species, complete or partial resistance has been documented in the distant relatives Murraya paniculate and Bergera koenigii, providing excellent systems to investigate molecular mechanisms leading to either resistance or susceptibility. The first weeks after bacterial release into the phloem are critical for the establishment of the bacteria. In this study, a thorough transcriptomic analysis of young flushes exposed to CLas-positive or negative psyllid has been performed in Citrus x sinensis, as well as in these resistant species along the first eight weeks after exposure. Our results suggest that the resistant genotypes do not deploy a classical immunity response. Instead, transcriptome changes are scarce and only a few genes are differentially expressed. Functional analysis suggest that primary metabolism and other basic cellular functions could be rewired in the resistant genotypes to limit infection. Transcriptomes of young flushes of the three species are very different, supporting the existence of distinct biochemical landscapes. These findings suggest that both intrinsic metabolic inadequacies to CLas survival, as well as inducible reprogramming of physiological functions upon CLas recognition, could orchestrate together to restrict bacteria multiplication in these resistant hosts.